IP addresses are based on actions, not just account creation. Feel free to contact staff if you think they are the same person, so basically most of what Hollowness mentioned you could do. Staff can look into more than just IP address, so they might get a conclusive answer on if they are connected or not.
Henry Hudson GC wrote:
I am an administrator on that wiki. I just want to have a good way to refute his claim so I have a good reason to block him.
So you are against getting staff involved? Staff can see if that IP address has 100 accounts or 2, wouldn't you want a more finite solution instead of just blocking the next same IP address account bugging you?